1. Field of the Invention
The present invention relates to a method and a communication apparatus for deciding a transmitting region for an allocated transmitting burst in a frame of an orthogonal frequency division multiplex access (OFDMA) system according to a plurality of burst regions.
2. Descriptions of the Related Art
The use of broadband services has increased with the rapid development of computer networks. However, only computer users in some areas of the world can obtain high-speed wired broadband services, such as digital subscribe line (DSL), cable broadband accessing service, etc. While network telecommunication service providers would like to expand the availability range of their broadband networks, the high construction costs for building wired networks prevents them from doing so. Therefore, developing wireless broadband network technologies has become a viable alternative. Present wireless network technologies include wide area network (WAN), metropolitan area network (MAN), local area network (LAN), and personal area network (PAN). Each technology applies to its own communication distance.
The IEEE 802.16e, or WiMAX, is a new wireless transmission standard which was initially established for metropolitan area network to provide the “last mile” wireless broadband connection technology. After improvements, the IEEE 802.16e can also support other market needs, such as various mobile and high-speed broadband applications. In contrast with the IEEE 802.11 (Wi-Fi) and 3G mobile communication technology, the IEEE 802.16e has a greater network broadband, lower building costs, better service quality, and better expansibility. Furthermore, it can assist and expand on Wi-Fi hot points.
A conventional OFDMA wireless communication system 1 based on the IEEE 802.16e is illustrated in FIG. 1. The OFDMA wireless communication system 1 comprises a base station (BS) 101 and a plurality of mobile stations (MSs) 103, 105, 107, 109. For brevity, the MSs will be denoted hereinafter as the first MS 103, second MS 105, third MS 107, and fourth MS 109. There are a plurality of frames used to transmit information and/or data between the BS 101 and the MSs 103˜109 in the OFDMA wireless communication system 1 as illustrated in FIG. 2. For brevity, the frames will be denoted hereinafter as frames 21, 23, 25. The frames 21, 23, 25 are allocated by a wireless communication apparatus, such as the BS 101. The x-axis in FIG. 2 represents the symbol axis, while the y-axis represents the sub-channel axis.
The frames 21, 23, 25 of the OFDMA wireless communication system 1 respectively comprise downlink sub-frames 211, 231, 251 and uplink sub-frames 213, 233, 253. Each of these sub-frames can be used for downlinking (BS to MSs) or uplinking (MSs to BS) information/data transmission to the OFDMA wireless communication system 1. In addition, each of the downlink sub-frames 211, 231, 251 respectively comprise Uplink-MAPs 2111, 2311, 2511, which are uplink bursts allocated by slots to different MSs 103˜109. Each of the uplink sub-frames 213, 233, 253 respectively comprises some control regions, such as ranging sub-channel regions or fast feedback regions.
In more detail, the Uplink-MAP 2111 of the downlink sub-frame 211 will allocate the following: an uplink burst 2333 with slots of the first MS 103, an uplink burst 2334 with slots of the second MS 105, an uplink burst 2335 with slots of the third MS 107, and an uplink burst 2336 with slots of the fourth MS 109. These uplink bursts will be allocated in the uplink sub-frame 233 using different information elements (not shown), aside from the ranging sub-channel 2331 and the fast feedback 2332. The information element of the first MS 103 in the Uplink-MAP 2111 allocates a sub-channel offset, a symbol offset, and a number of slots of the uplink burst 2333, while the information element of the second MS 105 in the Uplink-MAP 2111 allocates a sub-channel offset, a symbol offset, and a number of slots of the uplink burst 2334. Likewise, the information element of the third MS 107 in the Uplink-MAP 2111 allocates a sub-channel offset, a symbol offset, and a number of slots of the uplink burst 2335; while the information element of the fourth MS 109 in the Uplink-MAP 2111 allocates a sub-channel offset, a symbol offset, and a number of slots of the uplink burst 2336. Finally, the uplink bursts 2333˜2336 of the uplink sub-frame 233 can be described by the above specification and can be respectively transmitted with the allocated slots by each baseband processor of the MSs 103˜109.
In the same way, the Uplink-MAP 2311 of the downlink sub-frame 231 will allocate uplink bursts with slots of the MSs 103˜109 in the uplink sub-frame 253, and the Uplink-MAP 2511 of the downlink sub-frame 251 will allocate uplink bursts with slots of the MSs 103˜109 in the uplink sub-frame of the next frame (not shown).
With the information elements described above, uplink bursts of the MSs 103˜109 will be allocated in each uplink sub-frame for transmitting information/data from the MSs 103˜109 to BS 101. However, when the number of the MSs increases, the calculating time of allocating slots for each MS increases as well, thereby, reducing the transmitting efficiency of the OFDMA wireless communication system 1. Accordingly, it is important for the mobile communication providers and the mobile communication apparatus manufacturers to find a solution for improving the calculation time of allocating slots for each MS to increase the transmitting efficiency of the wireless communication system.